The invention disclosed and claimed herein deals with a piezoelectric transducer assemblies that are useful for the monitoring of the gas output from a diaphragm or bellows pump using air, nitrogen, or carbon dioxide as a working medium, wherein the transducer is not an integral part of the input or output flow stream of the material being pumped, but is used to sense the exhaust gas flow of the gas driven pump whereby the gas pump can be controlled. For purposes of this invention, what is meant by xe2x80x9cgas pumpsxe2x80x9d herein is pulsed gas output pumps of the diaphragm or bellows type.
The transducers of the invention disclosed herein are intended to replace those transducers currently used in monitoring the input flow of material being pumped by a gas driven pump, the output flow of materials being pumped by a gas driven pump, and/or the pressure of the input or output flow of material being pumped by a gas driven pump. Such transducers are, for example, magnetic Hall effect transducers, Light Emitting Diodes or photo optic transducers, and the like.
In understanding the invention disclosed herein, one must remember that there are essentially, at minimum, two flow streams in a situation wherein material is being pumped by a gas driven pump. The first is the flow stream provided by the gas that is being used to drive the pump, and the second, or other streams, are those provided by the material being handled by the pump, such as water, non-toxic fluids, aqueous acids, aqueous caustics and other hazardous, toxic, and other pump destructive materials.
With the invention herein, when describing xe2x80x9clowxe2x80x9d, it is meant that the discussion deals essentially with the flow of material being handled by the gas driven pump, and not the flow of gas being used to drive the gas driven pump, unless the gas flow stream is indicated otherwise.
The use of piezoelectric transducers to measure, monitor and track various events is not new in the art. Currently, manufacturers are using magnetic Hall effect transducers, photo optic transducers, Light Emitting Diode transducers and the like to monitor gas pumps, or measure events taking place in manufacturing processes where gas pumps are utilized, wherein most pumps in use today are air driven pumps.
Some pressure sensing applications in which piezoelectric transducers have been used are: the actual measurement of pressure; measuring impact forces through the use of accelerometers; use of microphones for recording or detection of sound; the generation of sounds and/or ultrasonic waves; and, the detection of passing automobiles or trains over strings of transducers.
The gas driven pump industry has used electronic feedback from operating pumps in some critical applications for a number of years. The feedback has been carried out in a number of ways. Traditionally, in gas operated pumps, at least one part typically reciprocates. Some pump manufacturers use electronically shifting shuttle valves within or attached to these pumps. Such shifting has been accomplished by a reciprocating portion of the pump being detected with a proximity transducer, or by a color-contrasting portion of a reciprocating part in the pump passing an electronic eye, which in turn sends an electronic signal to a shuttle valve. This movement in turn shifts the shuttle valve.
Other pump manufacturers have used both mechanical and solid-state pressure switches, which receive a blast of gas from valves inside the pump at the desired time of shuttle valve switching. The mechanical or solid-state pressure switch then translates the blast of gas into an electronic signal that is then sent on to the shuttle valve for operation of the shuttle valve. In addition, the electronic signals that are sent to the shuttle valve can and have been tapped by manufacturers to provide electronic signals to other apparatii that monitor the pumps. These apparatii include but are not limited to: cycle counting transducers, tachometers, overrun monitors, underrun monitors and personal computer systems which are embedded in tools which monitor pumps, among other things.
In every case, the use of such current equipment requires invasive transducer placement in the pump itself. This creates a situation where the parts placed in the interior of the pump cause contamination, or the parts are affected by the caustic, acid, or other destructive chemicals being handled by the pump. Such parts include, for example, flow meters, mass transducers, and paddle wheel transducers, all of which are placed directly in the flow of the materials being handled by the pump. In the case of foods, such parts create situations wherein the food is contaminated by trace metals and other materials. Also, the placement of these parts in the interior of the pump creates a situation wherein the parts act as plugs or create plugs, or partial plugs, in the flow of the material being handled by the pump, and in addition, these parts are difficult to replace or repair.
In other situations, owing to the above stated problems, pump systems are not monitored at all and this leads to malfunctions in component parts of the manufacturing process and thus also leads to expensive downtime, cleanup and myriad other problems. In these situations, the only time that the pump is monitored is when there is a major malfunction that happens to be noticed by those monitoring the manufacturing process. The ultimate is when these problems cause the pump to stop completely, which often leads to human injury and equipment destruction.
Thus, it would be valuable to have a means of monitoring and/or controlling gas driven pumps by a non-invasive transducer that would essentially eliminate all of the above-mentioned problems.
What are disclosed and claimed herein are piezoelectric transducers that provide non-invasive means for monitoring the exhaust ports of gas driven pumps to eliminate the above-mentioned problems.
The methods disclosed and claimed herein use the transducers described just above in conjunction with digital output electronics, in which a great number of digital output electronic configuration are known in the prior art today, to provide a means for monitoring gas driven pumps. Such methods enhance the performance of the pumps and the control of the pumps without the concomitant problems associated with transducers that are required to be inserted in the pumps per se. The transducers of this invention can be mounted as part of a gas diffuser, or can be remotely located, even at relatively long distances from the pump, such as, for example, when that pump is handling an explosive material.
The transducer assemblies of this invention, and the methods of this invention provide a plurality of benefits not obtainable by the transducers and methods of the prior art, such as the ability to keep all parts out of the gas pump, and especially metal parts from the diaphragm and/or bellows of the pump; ability to handle high end acid materials or caustic materials without destruction of the transducers; ability to start and stop gas pumps very quickly owing to the instantaneous response by the transducer to air flow events; allow precise monitoring and control of flow rates and metering applications; have the ability to verify priming of the gas pump and initiation of a restart of any operation, or any sequence of operation; they provide quick and easy retrofit to older or existing equipment; they can verify that the gas pump is actually operating; they have the capability of constant flow rate monitoring; they have the ability to shut down pumps on certain specified deviations from standards; they can control precise metering of fluids such as gallons, quarts, liters, ounces, or larger or smaller quantities, and, their use generally leads to more efficient and more reliable gas pump designs.
Thus, what is disclosed and claimed herein in one embodiment is a piezoelectric transducer assembly comprising in combination, an insertable transducer retainer assembly and a receiving transducer retainer assembly, the insertable transducer retainer assembly comprises a housing having an outside surface, a front and a back. The back has centered in it, a hub. The centered hub has a centered opening through it and the centered hub is integrally connected to the insertable transducer retainer assembly. The outside surface has a fastening means on it and a tapered front outside circumferential edge.
The insertable transducer retainer assembly has a first circular opening in the front, wherein the first circular opening has a circular piezoelectric transducer disposed in it. The piezoelectric transducer has a bottom surface and a top surface.
There is a second opening in the front of the insertable transducer retainer assembly, deeper than the first circular opening and having a lesser diameter than the diameter of the first circular opening.
The centered opening in the centered hub continues on through the transducer retainer assembly housing and opens into the second opening to provide a continuous channel through the transducer retainer assembly, which exits at the back of the hub. The piezoelectric transducer has electrical leads connected to its bottom surface.
The receiving transducer retainer assembly also has a housing. The receiving transducer retainer assembly housing has a front and a back, wherein the back has centered in it a hub integrally mounted on it. The receiving transducer retainer hub has a back and a front and is lesser in diameter than the diameter of the receiving transducer retainer assembly housing.
The front of the receiving transducer retainer assembly has located therein an opening. The receiving transducer retainer assembly opening has an interior surface and a bottom, wherein the interior surface has disposed on it, a fastening means compatible with the fastening means of the insertable transducer retainer assembly. The opening has a tapered circumferential edge at the bottom. There is a saucer-like depression below the bottom of the opening in the receiving transducer retainer assembly. The saucer-like depression has a bottom. The surface area of the top of the saucer-like depression is relative to the surface area of the top of the piezoelectric transducer, the surface area relationship having a ratio in the range of from zero to 1:1.
There is a channeled opening from the bottom of the saucer-like depression through the center of the receiving transducer retainer hub and the interior of the receiving transducer retainer hub has an adapting means for adapting the receiving transducer retainer assembly to a pump. The pump in this case is a gas pump, either of the bellows type air pump, or the diaphragm type air pump.
In a further embodiment of this invention, in the piezoelectric transducer, there is disposed over the top of the piezoelectric transducer, an elastomeric protective covering, typically in the form of a disk, the details of which are set forth infra.
In yet another embodiment of this invention, there is further disposed in the bottom of the second opening of the transducer retainer assembly, an electronic configuration, the details of which are provided infra.
In still another embodiment of this invention, there is disposed in the second opening a compressible material, the details of which are provided infra.
In addition, there is an embodiment of this invention in which there is provided at least one stiffening disk covering the piezoelectric transducer per se, the details of which are also provided infra.
In still another embodiment of this invention, there is set forth a system comprising an gas pump, a piezoelectric transducer assembly operably associated with the gas pump, and a control system for monitoring and controlling the gas pump.